UIColor 初始化程序（找不到接受 .... 的“UIColor”类型的初始化程序）错误 [重复]

Question

我知道这不是一种合适的方法，但为了学习，我有一个选择器控件，其中包含四个组件和每个 255 行来更改基于 RGB-alpha 的“视图”背景颜色。 我知道UIColor(red: <#CGFloat#>, green: <#CGFloat#>, blue: <#CGFloat#>, alpha: <#CGFloat#>) 接受四个浮点数作为每种颜色的参数，但我得到了错误：
找不到接受类型为“（红色：Float，绿色：Float，蓝色：Float，alpha：Float）”的参数列表的“UIColor”类型的初始化程序
怎么了？

func pickerView(pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {

    var newbackgroundColor = UIColor()

    var redCode: Float = 0.0
    var greenCode: Float = 0.0
    var blueCode: Float = 0.0
    var alphaCode: Float = 0.0

    if component == 0 {
        switch row {
        case 0..<256:
            redCode = Float(row/255)
            newbackgroundColor = UIColor(red: redCode, green: greenCode, blue: blueCode, alpha: alphaCode)
        default:
            break
        }

    } else if component == 1 {
        switch row {
        case 0..<256:
            greenCode = Float(row/255)
            newbackgroundColor = UIColor(red: redCode, green: greenCode, blue: blueCode, alpha: alphaCode)
        default:
            break
        }

    } else if component == 2{
        switch row {
        case 0..<256:
            blueCode = Float(row/255)
            newbackgroundColor = UIColor(red: redCode, green: greenCode, blue: blueCode, alpha: alphaCode)
        default:
            break
        }

    } else {
        switch row {
        case 0..<256:
            alphaCode = Float(row/255)
            newbackgroundColor = UIColor(red: redCode, green: greenCode, blue: blueCode, alpha: alphaCode)
        default:
            break
        }

    }

    self.view.backgroundColor = newbackgroundColor
}

Answer 1

使用CGFloat 而不是Float

遇到此类错误时请查看 API 文档

Answer 2

除了 Float 与 CGFloat 不同之外，您还可以像这样使它更容易：

class ViewController: UIViewController,UIPickerViewDelegate {
    @IBOutlet var pickerView: UIPickerView!
    func numberOfComponentsInPickerView(pickerView: UIPickerView) -> Int {
        return 4
    }
    func pickerView(pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
        return 256
    }
    func pickerView(pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
        view.backgroundColor = UIColor(red: CGFloat(pickerView.selectedRowInComponent(0))/255, green: CGFloat(pickerView.selectedRowInComponent(1))/255, blue: CGFloat(pickerView.selectedRowInComponent(2))/255, alpha: CGFloat(pickerView.selectedRowInComponent(3))/255)
    }
    func pickerView(pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String! {
        return "\(row)"
    }
    override func viewDidLoad() {
        super.viewDidLoad()
        pickerView.delegate = self
        pickerView.backgroundColor = UIColor.whiteColor()
    }
    override func viewDidAppear(animated: Bool) {
        pickerView.selectRow(255, inComponent: 0, animated: false)
        pickerView.selectRow(0, inComponent: 1, animated: false)
        pickerView.selectRow(0, inComponent: 2, animated: false)
        pickerView.selectRow(255, inComponent: 3, animated: false)
        view.backgroundColor = UIColor(red: CGFloat(pickerView.selectedRowInComponent(0))/255, green: CGFloat(pickerView.selectedRowInComponent(1))/255, blue: CGFloat(pickerView.selectedRowInComponent(2))/255, alpha: CGFloat(pickerView.selectedRowInComponent(3))/255)
    }
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }
}